In many industrial applications, various pipes, conduits, tubes and the like are designed to convey hot or cold materials such as steam, chemicals, hot oil, coolant, refrigerant, chilled water, warm and cooled air, etc. It is common practice to insulate such pipes not only to maintain the conveyed material as near as possible to desired temperature, but also, in the case of cold materials, to prevent "sweating" which occurs because of condensation of ambient moisture on a cool pipe surface, frequently with attendant rusting of parts. Furthermore, modern new technology construction codes frequently require that all pipes carrying materials of temperatures differing significantly from the ambient temperature must be insulated. Thus, the industry standard today maintains the integrity of the insulated pipe throughout its length.
In a typical construction application an insulated pipe will be displaced from the support structure such that it may be necessary to support it by virtue of hangers if the pipe is to be supported from above, by cantilevers if the pipe is to be supported from the side, and by pedestals if the pipe is to be supported from below. In each of these cases it is necessary that a firm contact restricting the pipe from movement in the directions perpendicular to its axis be achieved between the support member and the pipe.
To achieve a maximum insulating effect, it has been the usual practice to insulate the entire length of pipe and place a hanger on the outside in contact with the insulation. Consequently, the insulation itself acts as a structural member in supporting the pipe. The portions of such hangers contacting the insulation normally are of relatively narrow width, resulting in large stress concentrations over a small area of the insulation.
Since thermal pipe insulation is by nature porous and fragile, these stress concentrations of pressure over a relatively small area frequently crush the insulation. In time, often aided by vibration or jarring of the pipe, the crushed area continues to deteriorate, forming not only an unsightly appearance but, more seriously, reducing the desired insulating effect.
Consequently, it is necessary that the insulating material utilized have significant load-bearing capacity so as to prevent crushing of the insulating material and diminution of its insulating characteristics which requires much greater density and load-carrying ability than material which may be utilized at intermediate points wherein no load-carrying capacity is required. Such higher density load-carrying material is more costly to manufacture and machine than the lower density insulation utilized on the remainder of the pipe.
Conventionally, in long horizontal pipe runs, it has been necessary to support pipe by means of spaced clevis pipe hangers. In the event that the pipe required thermal or acoustical insulation, blocks were utilized to temporarily support the bared pipe in the pipe hangers. Such blocks would then be removed as special insulation was inserted around the pipe adjacent the pipe hanger. At each hanger is an insulation assembly, typically cylindrical, around which the hanger extends. Common materials used for making components of these insulation assemblies are calcium silicate, foam polymer, cellular or fibrous glass. Materials such as glass fiber or calcium silicate have the disadvantages of being brittle, having insufficient supporting strength, and lack of compressibility.
During installation of these systems, workmen who suspend the piping typically install the lower, generally semicylindrical block beneath the pipe when installing the hanger. The upper part is left to insulation installing workmen who subsequently install insulation jackets over the length of the pipe between the hangers. Insulation installers dislike the task of inserting the upper block and completing assembly of the hanger arrangement since it is difficult to get the various components properly assembled with each other while the pipe is suspended. Consequently, less than a desirable job is too often performed. Another fairly common occurrence is the tendency for the hanger to slip off the end of the installed lower insulation block. All of these factors detract from proper insulation and/or suspension of the pipe.
A number of patents granted between 1970 and 1993 featured the above techniques. One such may be found by Bindel in U.S. Pat. No. 3,575,214 which teaches in accordance with one form of his invention, a strap or band type of hanger bracket passing around a bared section of insulated pipe to make direct contact with it. In this manner, the pipe insulation is not used as a structural member and is never either in compression or tension. To provide a bared section, the pipe insulation may be cut away, or the normal pipe insulation may be otherwise spaced apart to leave the exposed section of pipe. A premolded insulating shell, preferably of foamed or cellular resinous material, covers a substantial portion, if not all, of the hanger rod and extends around the bracket to cover and thereby insulate it.
March in U.S. Pat. No. 3,539,137 discloses a supporting bracket which positions and supports a reinforced plastic saddle or a steel saddle covered with a protective corrosion-resistant coating. A vapor barrier jacketing is secured to the saddle and an engineered support member formed of insulating material, such as, for example, a high precompressed fiberglass support is secured to the vapor barrier jacketing. It should be noted that in the trade such a saddle is often referred to as an insulation shield or a pipe covering protective shield.
McClellan in U.S. Pat. No. 4,323,088 also teaches an insulating support device comprising a first insulating support member adapted to slidably engage a second insulating support member so as to form therewith a cylindrical solid having an axial hole therethrough for receiving a pipe. Meanwhile, Williams in U.S. Pat. No. 5,192,039 discloses a hanger insulation system having a unitary pipe insulation and shield assembly of upper and lower partially insulation elements defining a cylindrical pipe receiving cavity to form a clamshell arrangement extendable about a pipe to snap fasten the clamp elements together. Williams in U.S. Pat. No. 4,146,203 disclosed a different approach but also requiring the use of the insulation with his system rather than the insulation already existing on the length of a pipe.
These disclosed teachings were primarily designed to eliminate or reduce the concentrations of pressure over a relatively small area. Nevertheless, in so doing additional problems were created. For example, blocks for temporary support were required as was extra, special insulation around the pipe adjacent the spaced clevis pipe hangers. Furthermore, these techniques required that a bared section of pipe be esposed by cutting away the conventional pipe insulation and substituting special high density, load-carrying insulation to support the pipe.
As a result, the conventional method in use today rarely employs these techniques but provides a simple metal saddle having a much longer arc which in turn is welded to the bottom of the clevis hanger. This wider saddle substantially increases the surface area upon which the insulation rests thereby spreading the compression pressures more evenly and avoiding damage. Consequently, one now utilizes the original insulation on the pipe throughout the much simplified assembly operation.
Not withstanding, there are still many problems associated with this current metal saddle approach. For example, while clevis hangers are standard, readily available commercial articles, to weld a curved metal saddle the metal must first be rolled. Thus, a special order is required since it is a custom job with significant increase in cost and substantial delays in receipt. Typically, the metal saddle is either welded to the hanger or to a support channel. The metal saddle and weld still promotes corrosion thereof as well as of the hanger reducing lifetime of the fixture; the presence of moisture, of course, aggravates corrosion of the metal.
Since metal saddles are relatively inflexible, several different sizes are required even for a standard clevis hanger in order to accomodate different sizes of insulated pipe. Thermal conductivity of the metal reduces the efficiency of the insulation. Edges of the metal saddles are rough thereby contributing to tearing of the pipe insulation.
While direct metal-to-metal welding or clamping is the strongest and securest and thus preferable for this purpose alone, several difficulties arise in connection with this practice wherein the pipe must be insulated. Even if the clamp or weld is subsequently wrapped or coated with insulation, there remains a conductive heat transfer path through the clamp or weld to the support structure, thus generating a significant heat transfer between the environment and the pipe. This substantially defeats the purpose of the insulation.
None of these prior art devices utilized for supporting and insulating pipes solve all of these problems. That is, none can satisfy these requirements while maintaining easy and economical manufacture, easy on-site assembly, reduction in labor hours and related cost while providing a superior assembly with considerable increased safety to the workers.
It is therefore an object of the present invention to provide a support device for insulated pipes which is capable of providing strong, lateral support in combination with effective insulation, adapted for easy assembly on the job site, simple in structure, and economical to manufacture.
It is another object to do the above by utilizing a plastic saddle having a clip portion in conjunction with a clevis hanger thereby eliminating the need for welding.
It is an object of the present invention to do the above by utilizing a plastic saddle having a drop-in twist-and-lock portion in conjunction with a support channel thereby eliminating the need for welding.
It is also an object to avoid the need for special insulation materials.
It is a further object to introduce enough flexibility into a single saddle to provide an adequate fit for several different size pipes.
It is still another object to substantially reduce the tendency of corrosion.
It is yet another object to substantially reduce thermal conductivity losses.
An additional object is to avoid the need to remove insulation and expose the bare pipe thereby using the insulated or noninsulated pipe as one finds it.
Another object of the instant invention is a major improvement in the method of fastening the saddle to a clevis hanger or a cross channel support thereby reducing labor costs.
A further object of the invention is to provide a means for retrofitting poorly installed insulated pipes which lay on a clevis hanger or a support channel in the absence of a shield or saddle of any kind.